the Genus FIstulipora, M'Goy. 515 



of tlie cells. The raesopores are sufficiently numerous to 

 completely isolate the autopores from each other ; they exhibit 

 the usual polygonal form. A few, of a comparatively large 

 size, occupy the central portions of the " raaculte," and towards 

 these the folds of the autopores are directed. Longitudinal 

 sections show the finely vesicular character of the tabulge in 

 the mesopores and the growth of the corallum in concentric 

 layers. These sections also show that the autopores diverge 

 in a flabellate manner from tlieir centres of growth. A like 

 feature is also noticeable in F. cornamca (PL XVIII. fig. 2 c). 



Ohs. The present form has been well known to us for more 

 than a year, but we have not till now been in a position to 

 publish a description of it. In the meantime Professor 

 Schliiter, of Bonn, has been before us in the matter. As, 

 however, that author has given neither figures nor measure- 

 ments of his species, we have felt ourselves justified in re- 

 describing it and supplying those deficiencies, more especially 

 as it exhibits in a marked degree one of the most characteristic 

 features of the genus, viz. those remarkable folds in the walls 

 of the autopores. 



In its general structural features this species resembles 

 F. cornavica^ Nich. & Foord [infra). The two species are 

 figured upon the same Plate (XVIIl.) to facilitate comparison. 

 It will be seen that the corallites of F. cornamca are larger 

 than those of F. trifoliata^ and also that the autopores in the 

 latter are more highly developed than they are in the former. 



We are indebted to Prof. Schliiter for sections of F. tri- 

 foUata^ which place beyond question the specific identity of 

 his species with ours, a point which we were unable to decide 

 from his description alone. 



Formation and Locality. Somewhat rare in the Middle 

 Devonian of Gees, near Gerolstein, Eifel. 



Fistulipora cornamca "^^ Nich & Foord. 

 (PI. XVIIL figs. 2-2 c.) 



Corallum subhemispherical, attached by its base to shells 

 or other marine objects ; composed of a succession of thin 

 concentric layers, which apparently mark periodical cessa- 

 tions of growth. Surface monticulose, the " monticules " 

 consisting of mesopores. Autopores, as seen in transverse 

 sections, irregularly ovate, the folds occupying about one 

 fourth of the circumference of their walls. About four of the 

 autopores fill the space of 1 millim. Mesopores nume- 



* The Oornavii were a tribe of ancient Britons who, along with the 

 Ordovices, inhabited Shropshire at the time of the Roman invasion. 



35* 



